Primer effects on ES and SD

[Lefty Trigger]

Just for kicks this week I loaded up my "general purpose" load in my 6.5 Grendel bolt rifle, same brass, same bullet, same powder and load and only changed primers. I loaded 5 rounds of each and ran them across my LabRadar for some numbers. The results were interesting...

Federal 205 / velocity 2381 / ES 23 / SD 8.5
Federal 205M / velocity 2388 / ES 19 / SD 7.4
Remington 7 1/2 / velocity 2385 / ES 50 / SD18.8
CCI 400 / velocity 2378 / ES 26 / SD 9.8
CCI 450 / velocity 2386 / ES 32 / SD 13.1
CCI BR4 / velocity 2380 / ES 19 / SD 7.4

 

[Straightshooter1]

Now you just have to do it again with the same brass to see if you get very similar results.

 

[INTJ]

To really blow your mind, get the K&M Gauge which will allow you to seat each primer in each case at exactly the amount of crush your want.

 

[Cap'n]

I'd be very surprised if these small samples actually represent statistically significant differences.

 

[Lefty Trigger]

I'd be very surprised if these small samples actually represent statistically significant differences.

Donate the bullets and primers and I'll run 100 of each to how much change there is,... LOL

 

[Liven The Dream]

Your test is proof to me I answered a post correct !
What is the Difference between 205 and 205M ? A few feet per second and Lower SD .

7 1/2 Rem. I never got lower SD using them .

Thanks for the post .

 

[Lefty Trigger]

Your test is proof to me I answered a post correct !
What is the Difference between 205 and 205M ? A few feet per second and Lower SD .

7 1/2 Rem. I never got lower SD using them .

Thanks for the post .

Yeah, what surprised me is the BR4 and the 205M almost identical.

 

[Tommie]

Yeah, what surprised me is the BR4 and the 205M almost identical.

When I’ve been load testing those two primers have given nearly identical results.

 

[DRNewcomb]

What's your standard load powder? Primers and powders need to match. If you use a hard-to-ignite powder, you may need a magnum primer, while "soft" primers may be best for some stick powders.

 

[shoot4fun]

Funny how some, such as 6BR and 6 Dasher, are CCI450 gospel. I’ve always shot CCI450 in long-range BR in the BR, Dasher and even my 6.5-47L. I did primer testing on my 223 load of Varget and 80 Berger VLD on a whim. The load had already established a high accuracy standard. I used match prepped Lapua brass (once fired) and only changed primers up between CCI400, 450 and BR4 along with Rem 7 1/2 and Federal 205 and 205M. The CCI400 was best by far for my test and has shown improved results over for 2019 and so far this year as well all in a broad range of weather conditions.
This is only one situation though and all it proves is one primer may be better than another for one particular load or rifle. I won’t worry over primer selection for the most part though. Especially true if I am seeing good results.

 

[SGK]

I'd be very surprised if these small samples actually represent statistically significant differences.

They don't

 

[INTJ]

They don't

I sure have been bumped out of the top spot many times in LR BR by statistically insignificant differences.

The difference between 4.939" and 5.376" 6-target aggs at 1000 yds is not statistically significant, yet that was the difference between first and third places.

Because of that, when I drop my ES from low teens to high single digits consistently by weighing primers and seating with a tool that ensures exactly .002" crush on every BR-4 in every case, I'll take it. It won't show up on every target, but it will sometimes.......

 

[Lefty Trigger]

What's your standard load powder? Primers and powders need to match. If you use a hard-to-ignite powder, you may need a magnum primer, while "soft" primers may be best for some stick powders.

This load was using Accurate 2460 which is a ball powder.

 

[SGK]

Lefty posted 6 sets of 5 samples. The average and SD listed for each are valid for the sample sets only. The numbers are not measures of the underlying "primer" populations. We can only have confidence that the population mean and SD are within ranges around those numbers and the breadth of those ranges depends on the degree of confidence we desire. You can actually use statistics to determine whether you can be confident - or not - that the differences noted in sampling are actually differences at all - whether they are statistically different - or whether they are just two sample sets of the SAME underlying population. At this page, there is a link to a very useful online calculator. Lefty can key in the 5 numbers for each sample set and see if they do indicate meaningful differences. Wouldn't take long. If you are going to undertake these sorts of tests it's worth understanding whether the results show anything at all. Maybe they do. Maybe they don't.

https://www.autotrickler.com/stats-calculator.html

 

[ronemus]

I've tested using 10- and 20-shot strings and see similar differences between primers, all else constant. The differences in performance of loads using different primers are real.

 

[bozo699]

Yeah, what surprised me is the BR4 and the 205M almost identical.

There all made in Lewiston Idaho at Vista Outdoors except the 7 1/2
Wayne

 

[Longtrain]

With everything else being equal, a primer change can change your loads’ performance. Loading my Dasher, SD’s ran all over the place using WSR, BR4, 7 1/2, 556M, CCI400, Wolf SRM, consistent with multiple 10 shot strings. Same batch of cases, powder lot, bullet and seating depth. Tula 556M’s have been the most consistent in SD, always under a SD of 6 in the Dasher.

 

[Lefty Trigger]

The only point I'm trying to make is the primers DO make a difference in load workup. There are a couple of younger guys in our club handloading and swear that they have to find the exact primer listed "in the book" and they will get the exact same results. I have tried to point out that they should experiment and try other primers and MAY or MAY NOT see an improvement with end results.

 

[SGK]

Lefty, give the calculator a go. The problem is that you can't draw any conclusions one way or the other from what you've presented in the first post. When presenting results such as the ones you did you need to also present the confidence interval numbers. The most often used CI is 95%. Your posted results are for the sample set only and not for the population (behavior) you are trying to test. The difference is very important.

I'm not saying primers don't make a difference. I'm merely pointing out how to properly interpret the results of your test. You've not posted the relevant numbers.

 

[DRNewcomb]

..... There are a couple of younger guys in our club handloading and swear that they have to find the exact primer listed "in the book" and they will get the exact same results. I have tried to point out that they should experiment and try other primers and MAY or MAY NOT see an improvement with end results.

Have you mentioned to them that this is like using a recipe from Kraft and insisting that only Kraft mozzarella cheese will do? When loading manuals list specific brands of primers, it's not an accident; it's product placement.